Hydraulic oil control valve and valve timing adjustment device

ABSTRACT

A hydraulic oil control valve is coaxially disposed with a rotational axis of a valve timing adjustment device for adjusting valve timing of a valve. The valve is selectively opened or dosed by a drive shaft receiving a driving force from a drive shaft. The hydraulic oil control valve includes a tubular sleeve and a spool that is slidably moved within the sleeve. The sleeve includes an inner sleeve and an outer sleeve that is fixed to an end portion of one of the drive shaft and the driven shaft with an axial force. When the axial force is not applied, a minimum clearance between the outer sleeve and the inner sleeve in a radial direction is larger than a minimum clearance between the inner sleeve and the spool in the radial direction.

CROSS REFERENCE TO RELATED APPLICATION

The present application is a continuation application of International Patent Application No. PCT/JP2020/012843 filed on Mar. 24, 2020, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2019-055892 filed on Mar. 25, 2019. The entire disclosures of all of the above applications are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a hydraulic oil control valve used for a valve timing adjustment device.

BACKGROUND

A hydraulic valve timing adjustment device capable of adjusting a valve timing of an intake valve or an exhaust valve of an internal combustion engine has been known. The hydraulic oil control valve has a double-structure sleeve including a tubular outer sleeve and an inner sleeve. The outer sleeve is fastened to an end portion of a camshaft and a spool slidably moves within the inner sleeve to switch oil channels.

SUMMARY

A hydraulic oil control valve is used for a valve timing adjustment device. The valve timing adjustment device is configured to adjust valve timing of a valve and fixed to an end portion of one of a drive shaft and a driven shaft. The driven shaft is configured to selectively open and close the valve with a driving force transmitted from the drive shaft. The hydraulic oil control valve is coaxially disposed with a rotational shaft of the valve timing adjustment device and configured to control a flow of a hydraulic oil supplied from a hydraulic oil supply source. The hydraulic oil control valve includes a tubular sleeve and a spool. The spool has an end portion in contact with an actuator and is slidably moved by the actuator in an axial direction within the sleeve. The sleeve includes an inner sleeve and an outer sleeve. The inner sleeve is disposed radially outside of the spool. The outer sleeve defines therein an axial hole extending in the axial direction, The inner sleeve is inserted into at least a portion of the axial hole. The outer sleeve is fixed to the end portion of the one of the drive shaft and the driven shaft when an axial force is applied to the outer sleeve in the axial direction. When the axial force is not applied, a minimum clearance in a radial direction between the outer sleeve and the inner sleeve is larger than a minimum clearance in the radial direction between the inner sleeve and the spool.

A hydraulic oil control valve is used for a valve timing adjustment device. The valve timing adjustment device is configured to adjust valve timing of a valve and fixed to an end portion of one of a drive shaft and a driven shaft. The driven shaft is configured to selectively open and close the valve with a driving force transmitted from the drive shaft. The hydraulic oil control valve is coaxially disposed with a rotational shaft of the valve timing adjustment device and configured to control a flow of a hydraulic oil supplied from a hydraulic oil supply source. The hydraulic oil control valve includes a tubular sleeve and a spool. The spool has an end portion in contact with an actuator and is slidably moved by the actuator in the axial direction within the sleeve. The sleeve includes an inner sleeve and an outer sleeve. The inner sleeve is disposed radially outside of the spool. The outer sleeve defines therein an axial hole extending in the axial direction and the inner sleeve is inserted into at least a portion of the axial hole, The outer sleeve is fixed to the end portion of the one of the drive shaft and the driven shaft when an axial force is applied to the outer sleeve in the axial direction. When a predetermined condition is satisfied, the outer sleeve is in contact with the inner sleeve in the radial direction. The predetermined condition includes a condition that the axial force is applied to the outer sleeve

BRIEF DESCRIPTION OF DRAWINGS

The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:

FIG. 1 is a cross-sectional view showing a schematic configuration of a valve timing adjustment device including a hydraulic oil control valve of a first embodiment;

FIG. 2 is a cross-sectional view taken along a line II-II in FIG. 1;

FIG. 3 is a cross-sectional view showing a detailed configuration of the hydraulic oil control valve;

FIG. 4 is an exploded perspective view showing a detailed configuration of the hydraulic oil control valve;

FIG. 5 is a cross-sectional view showing a state where a spool is in contact with a stopper;

FIG. 6 is a cross-sectional view showing a state where the spool is located substantially at a center in a sliding area;

FIG. 7 is a cross-sectional view showing a schematic configuration of a hydraulic oil control valve of another third embodiment.

DESCRIPTION OF EMBODIMENTS

To begin with, examples of relevant techniques will be described.

Conventionally, a hydraulic valve timing adjustment device capable of adjusting a valve timing of an intake valve or an exhaust valve of an internal combustion engine has been known. In the hydraulic valve timing adjustment device, a supply of a hydraulic oil into hydraulic chambers defined by a vane rotor in a housing and a discharge of the hydraulic oil from the hydraulic chambers may be achieved by a hydraulic oil control valve disposed in a center portion of the vane rotor. For example, a hydraulic oil control valve has a double-structure sleeve including a tubular outer sleeve and an inner sleeve. The outer sleeve is fastened to an end portion of a camshaft and a spool slidably moves within the inner sleeve to switch oil channels.

Since the hydraulic oil control valve has the sleeve having a double-structure, the hydraulic oil may leak not only through a clearance between the inner sleeve and the spool but also through a clearance between the outer sleeve and the inner sleeve. Thus, an amount of the hydraulic oil leaking from the hydraulic oil control valve as a whole may increase. Therefore, the inventor of the present disclosure considered reducing a radial clearance between the outer sleeve and the inner sleeve to suppress the increase in the amount of the leakage. However, the inventor of the present disclosure has found that when the outer sleeve is fastened to an end portion of the camshaft, the outer sleeve contracts in the radial direction by an axial force of the fastening, which may deteriorate a slidability of the spool. Therefore, a technique for suppressing an increase in the amount of the leakage of the hydraulic oil while suppressing deterioration of the slidability of the spool is needed.

The present disclosure has been made to solve at least a part of the above issues and can be implemented as the following embodiments.

According to one embodiment of the present disclosure, a hydraulic oil control valve is provided. The hydraulic oil control valve is used for a valve timing adjustment device. The valve timing adjustment device is configured to adjust valve timing of a valve and fixed to an end portion of one of a drive shaft and a driven shaft. The driven shaft is configured to selectively open and close the valve with a driving force transmitted from the drive shaft. The hydraulic oil control valve is coaxially disposed with a rotational shaft of the valve timing adjustment device and configured to control a flow of a hydraulic oil supplied from a hydraulic oil supply source. The hydraulic oil control valve includes a tubular sleeve and a spool. The spool has an end portion in contact with an actuator and is slidably moved by the actuator in an axial direction within the sleeve. The sleeve includes an inner sleeve and an outer sleeve. The inner sleeve is disposed radially outside of the spool, The outer sleeve defines therein an axial hole extending in the axial direction. The inner sleeve is inserted into at least a portion of the axial hole. The outer sleeve is fixed to the end portion of the one of the drive shaft and the driven shaft when an axial force is applied to the outer sleeve in the axial direction. When the axial force is not applied, a minimum clearance in a radial direction between the outer sleeve and the inner sleeve is larger than a minimum clearance in the radial direction between the inner sleeve and the spool.

According to the hydraulic oil control valve, when the axial force is not applied, the minimum clearance between the outer sleeve and the inner sleeve in the radial direction is larger than the minimum clearance between the inner sleeve and the spool in the radial direction. Generally, in a hydraulic oil control valve that changes oil channels by sliding the spool, different portions in the axial direction are sealed according to the stroke of the spool, Thus, a length in the axial direction in the minimum clearance, which is defined between the inner sleeve and the spool in the radial direction, is set shorter than the stroke of the spool. Therefore, hydraulic oil is likely to leak through the minimum clearance between the inner sleeve and the spool in the radial direction. Further, the inner sleeve does not move relative to the outer sleeve in the axial direction. Therefore, a length in the axial direction of the minimum clearance, which is defined between the outer sleeve and the inner sleeve in the radial direction, is set to a relatively long value. Therefore, hydraulic oil is less likely to leak through the minimum clearance between the outer sleeve and the inner sleeve in the radial direction. From these facts, in case that the radial clearances are secured to suppress a deterioration of the slidability of the spool even if the axial force fixing the hydraulic oil control valve elastically deforms and contracts the outer sleeve, an increase of the amount of the hydraulic oil leakage can be suppressed compared to a configuration in which a magnitude relationship of the radial clearances are different from that of the present disclosure. Therefore, it is possible to suppress an increase in leakage amount of the hydraulic oil while suppressing deterioration of the slidability of the spool.

According to another aspect of the present disclosure, a hydraulic oil control valve is provided. The hydraulic oil control valve is used for a valve timing adjustment device. The valve timing adjustment device is configured to adjust valve timing of a valve and fixed to an end portion of one of a drive shaft and a driven shaft. The driven shaft is configured to selectively open and close the valve with a driving force transmitted from the drive shaft. The hydraulic oil control valve is coaxially disposed with a rotational shaft of the valve timing adjustment device and configured to control a flow of a hydraulic oil supplied from a hydraulic oil supply source. The hydraulic oil control valve includes a tubular sleeve and a spool. The spool has an end portion in contact with an actuator and is slidably moved by the actuator in the axial direction within the sleeve. The sleeve includes an inner sleeve and an outer sleeve. The inner sleeve is disposed radially outside of the spool. The outer sleeve defines therein an axial hole extending in the axial direction and the inner sleeve is inserted into at least a portion of the axial hole. The outer sleeve is fixed to the end portion of the one of the drive shaft and the driven shaft when an axial force is applied to the outer sleeve in the axial direction. When a predetermined condition is satisfied, the outer sleeve is in contact with the inner sleeve in the radial direction. The predetermined condition includes a condition that the axial force is applied to the outer sleeve

According to the hydraulic oil control valve, the outer sleeve 30 and the inner sleeve 40 are in contact with each other in the radial direction when the predetermined condition including the condition that the axial force is applied is satisfied, so that an increase in the amount of the hydraulic oil leaking through the radial minimum clearance between the outer sleeve and the inner sleeve can be suppressed. Further, since the contact between the outer sleeve and the inner sleeve in the radial direction can restrict the inner sleeve from expanding in the radial direction, an increase in the radial clearance between the inner sleeve and the spool can be suppressed and an increase in the amount of the hydraulic oil leaking through the clearance can be suppressed. Thus, even in a configuration in which the minimum radial clearance between the inner sleeve and the spool is secured to suppress the deterioration of the slidability of the spool, an increase in a leakage amount of the hydraulic oil can be suppressed. That is, an increase in the leakage amount of the hydraulic oil is suppressed while suppressing the deterioration of the slidability of the spool.

The present disclosure can be realized as the following embodiments. For example, it can be realized in a method for manufacturing a hydraulic oil control valve, a valve timing adjustment device provided with a hydraulic oil control valve, a method for manufacturing the valve timing adjustment device, and the like.

A. First Embodiment A-1. Device Configuration

A valve timing adjustment device 100 shown in FIG. 1 is used for an internal combustion engine 300 of a vehicle (not shown) and configured to adjust valve timing of a valve that is opened or closed by a camshaft 320 to which a driving force is transmitted from a crankshaft 310. The valve timing adjustment device 100 is provided in a power transmission path from the crankshaft 310 to the camshaft 320. More specifically, the valve timing adjustment device 100 is fixed to an end portion 321 of the camshaft 320 in a direction along a rotational axis AX of the camshaft 320 (hereinafter, referred to as “an axial direction AD”). A rotational axis AX of the valve timing adjustment device 100 substantially coincides with the rotational axis AX of the camshaft 320. The valve timing adjustment device 100 of the present embodiment is configured to adjust valve timing of an intake valve 330 among the intake valve 330 and an exhaust valve 340.

The end portion 321 of the camshaft 320 defines a shaft hole portion 322 and a supply inlet 326. The shaft hole portion 322 extends in the axial direction AD. The shaft hole portion 322 has a shaft fixing portion 323 on an inner circumferential surface of the shaft hole portion 322 to fix a hydraulic oil control valve 10 which will be described later. The shaft fixing portion 323 has a female thread portion 324. The female thread portion 324 is configured to be screwed with a male thread portion 33 formed in a fixing portion 32 of the hydraulic oil control valve 10, The supply inlet 326 extends in a radial direction and passes through an outer circumferential surface of the camshaft 320 to fluidly connect between the outer circumferential surface and the shaft hole portion 322. Hydraulic oil is supplied into the supply inlet 326 from a hydraulic oil supply source 350. The hydraulic oil supply source 350 includes an oil pump 351 and an oil pan 352. The oil pump 351 pumps the hydraulic oil stored in the oil pan 352.

As shown in FIGS. 1 and 2, the valve timing adjustment device 100 includes a housing 120, a vane rotor 130, and the hydraulic oil control valve 10, In FIG. 2, illustration of the hydraulic oil control valve 10 is omitted.

As shown in FIG. 1, the housing 120 includes a sprocket 121 and a case 122. The sprocket 121 is fit to the end portion 321 of the camshaft 320 and rotatably supported. The sprocket 121 defines a fitting recessed portion 128 at a position corresponding to a lock pin 150 which will be described later, An annular timing chain 360 is disposed around the sprocket 121 and a sprocket 311 of the crankshaft 310. The sprocket 121 is fixed to the case 122 with multiple bolts 129. Thus, the housing 120 rotates together with the crankshaft 310. The case 122 has a bottomed tubular shape and an opening end of the case 122 is closed by the sprocket 121. As shown in FIG. 2, the case 122 includes multiple partition walls 123 that protrude radially inward and are arranged in a circumferential direction with each other. Spaces defined between adjacent ones of the partition walls 123 in the circumferential direction serve as hydraulic chambers 140. As shown in FIG. 1, the case 122 defines an opening 124 at a center of a bottom portion of the case 122.

The vane rotor 130 is housed inside the housing 120 and configured to rotate in a retard direction or in an advance direction relative to the housing 120 in accordance with a pressure of the hydraulic oil supplied from the hydraulic oil control valve 10 which will be described later. Therefore, the vane rotor 130 serves as a phase shifting portion configured to shift a phase of a driven shaft relative to a drive shaft. The vane rotor 130 includes multiple vanes 131 and a boss 135.

As shown in FIG. 2, the multiple vanes 131 protrude radially outward from the boss 135 that is located at a center of the vane rotor 130 and are arranged adjacent to each other in the circumferential direction. The vanes 131 are housed respectively in the hydraulic chambers 140 and divide the hydraulic chambers 140 in the circumferential direction into retard chambers 141 and advance chambers 142. Each of the retard chambers 141 is located on one side of the vane 131 in the circumferential direction. Each of the advance chambers 142 is located on the other side of the vane 131 in the circumferential direction. One of the multiple vanes 131 defines a housing hole 132 extending in the axial direction. The housing hole 132 is in communication with the retard chamber 141 through a retard chamber pin control oil channel 133 defined in the vane 131 and in communication with the advance chamber 142 through an advance chamber pin control oil channel 134. The lock pin 150 is housed in the housing hole 132 such that the lock pin 150 can reciprocate in the axial direction AD in the housing hole 132. The lock pin 150 is configured to restrict the vane rotor 130 from rotating relative to the housing 120 and restrict the vane rotor 130 from coming into contact with the housing 120 in the circumferential direction when the hydraulic pressure is insufficient. The lock pin 150 is biased in the axial direction AD toward the fitting recessed portion 128 formed in the sprocket 121 by a spring 151.

The boss 135 has a tubular shape and is fixed to the end portion 321 of the camshaft 320. Therefore, the vane rotor 130 having the boss 135 is fixed to the end portion 321 of the camshaft 320 and rotates together with the camshaft 320 in an integral manner. The boss 135 defines a through hole 136 passing through the boss 135 in the axial direction at a center of the boss 135. The hydraulic oil control valve 10 is arranged in the through hole 136. The boss 135 defines multiple retard channels 137 and multiple advance channels 138. The retard channels 137 and the advance channels 138 pass through the boss 135 in the radial direction. The retard channels 137 and the advanced channels 138 are arranged adjacent to each other in the axial direction AD. The retard channels 137 fluidly connect between the retard chambers 141 and retard ports 27 of the hydraulic oil control valve 10 which will be described later. The advance channels 138 fluidly connect between the advance chambers 142 and advance ports 28 of the hydraulic oil control valve 10 which will be described later. In the through hole 136, a space between the retard channels 137 and the advance channels 138 is sealed by an outer sleeve 30 of the hydraulic oil control valve 10 which will be described later.

In the present embodiment, the vane rotor 130 are made of an aluminum alloy, but a material of the vane rotor 130 is not limited to the aluminum alloy and may be any metal material such as iron or stainless steel, a resin material, or the like.

As shown in FIG. 1, the hydraulic oil control valve 10 is coaxially arranged with the rotational axis AX of the valve timing adjustment device 100 and configured to control a flow of the hydraulic oil supplied from the hydraulic oil supply source 350. The operation of the hydraulic oil control valve 10 is controlled by an ECU (not shown) that controls an overall operation of the internal combustion engine 300. The hydraulic oil control valve 10 is driven by a solenoid 160 arranged on a side of the hydraulic oil control valve 10 opposite to the camshaft 320 in the axial direction AD. The solenoid 160 has an electromagnetic portion 162 and a shaft 164. The solenoid 160 moves the shaft 164 in the axial direction AD when the electromagnetic portion 162 is energized by instructions from the ECU. Thereby, the shaft 164 presses a spool 50 of the hydraulic oil control valve 10, which will be described later, toward the camshaft 320 against a biasing force of the spring 60. As will be described later, the spool 50 slides in the axial direction AD by being pressed, so that oil channels can be switched between oil channels in communication with the retard chambers 141 and oil channels in communication with the advance chambers 142.

As shown in FIGS. 3 and 4, the hydraulic oil control valve 10 includes a sleeve 20, the spool 50, the spring 60, a fixing member 70, and a check valve 90. FIG. 3 is a cross-sectional view taken along the rotational axis AX.

The sleeve 20 includes the outer sleeve 30 and an inner sleeve 40. Each of the outer sleeve 30 and the inner sleeve 40 substantially has a tubular shape. The sleeve 20 has a schematic configuration in which the inner sleeve 40 is inserted into an axial hole 34 defined in the outer sleeve 30.

The outer sleeve 30 forms an outer contour of the hydraulic oil control valve 10 and is disposed radially outside of the inner sleeve 40. The outer sleeve 30 has a main body 31, the fixing portion 32, a protrusion 35, a large diameter portion 36, a movement restricting portion 80, and a tool engaging portion 38. The main body 31 and the fixing portion 32 define therein the axial hole 34 extending along the axial direction AD. The axial hole 34 passes through the outer sleeve 30 in the axial direction AD.

The main body 31 has a tubular appearance and is arranged in the through hole 136 of the vane rotor 130 as shown in FIG. 1. As shown in FIG. 4, the main body 31 defines multiple outer retard ports 21 and multiple outer advance ports 22. The multiple outer retard ports 21 are arranged adjacent to each other in the circumferential direction and pass through the main body 31 between an outer circumferential surface of the main body 31 and the axial hole 34. The multiple outer advance ports 22 are defined between the outer retard ports 21 and the solenoid 160 in the axial direction AD. The multiple outer advance ports 22 are arranged adjacent to each other in the circumferential direction and pass through the main body 31 between the outer circumferential surface of the main body 31 and the axial hole 34.

The fixing portion 32 has a tubular shape and is connected to the main body 31 in the axial direction AD. The fixing portion 32 has a diameter substantially the same as that of the main body 31 and is inserted into the shaft fixing portion 323 of the camshaft 320 as shown in FIG. 1. The fixing portion 32 has the male thread portion 33. The male thread portion 33 is configured to be screwed with the female thread portion 324 of the shaft fixing portion 323. The male thread portion 33 and the female thread portion 324 are fastened to each other, so that an axial force in the axial direction AD toward the camshaft 320 is applied to the outer sleeve 30 and the outer sleeve 30 is fixed to the end portion 321 of the camshaft 320. Because the outer sleeve 30 is fixed with the axial force applied to the outer sleeve 30, it is possible to prevent the hydraulic oil control valve 10 from being displaced from the end portion 321 of the camshaft 320 due to an eccentric force of the camshaft 320 pushing the intake valve 330. Thus, it is possible to restrict the hydraulic oil from leaking.

The protrusion 35 protrudes radially outward from the main body 31. As shown in FIG, 1, the protrusion 35 holds the vane rotor 130 between the protrusion 35 and the end portion 321 of the camshaft 320 in the axial direction AD.

As shown in FIG. 3, the large diameter portion 36 is formed in an end portion of the main body 31 closer to the solenoid 160. The large diameter portion 36 has an inner diameter larger than those of other portions of the main body 31. In the large diameter portion 36, a flange portion 46 of the inner sleeve 40, which will be described later, is arranged.

The movement restricting portion 80 is configured as a stepped portion in the radial direction on the inner circumferential surface of the outer sleeve 30, which is formed by the large diameter portion 36. The movement restricting portion 80 holds the flange portion 46 of the inner sleeve 40, which will be described later, between the movement restricting portion 80 and the fixing member 70 in the axial direction AD. As a result, the movement restricting portion 80 restricts the inner sleeve 40 from moving in a direction away from the electromagnetic portion 162 of the solenoid 160 in the axial direction AD.

The tool engaging portion 38 is formed between the protrusion 35 and the solenoid 160 in the axial direction AD. The tool engaging portion 38 is configured to be engaged with a tool such as a hexagon socket (not shown) and used for fastening and fixing the hydraulic oil control valve 10 including the outer sleeve 30 to the end portion 321 of the camshaft 320.

The inner sleeve 40 has a tubular portion 41, a bottom portion 42, multiple retard protruding walls 43, multiple advance protruding walls 44, a sealing wall 45, the flange portion 46, and a stopper 49.

The tubular portion 41 substantially has a tubular shape and is located radially inside of the outer sleeve 30 between the main body 31 and the fixing portion 32. As shown in FIGS. 3 and 4, the tubular portion 41 defines retard supply ports SP1, advance supply ports SP2, and recycling ports 47. The retard supply ports SP1 are defined between the retard protruding walls 43 and the bottom portion 42 in the axial direction AD and pass through the tubular portion 41 between an outer circumferential surface and an inner circumferential surface of the tubular portion 41. In the present embodiment, the multiple retard supply ports SP1 are arranged on a half circumference of the tubular portion 41 in the circumferential direction. However, the multiple retard supply ports SP1 may be arranged on an all circumference of the tubular portion 41 or the tubular portion 41 may have a single retard supply port SP1. The advance supply ports SP2 are defined between the advance protruding walls 44 and the solenoid 160 in the axial direction AD and pass through the tubular portion 41 between the outer circumferential surface and the inner circumferential surface of the tubular portion 41. In the present embodiment, the multiple advance supply ports SP2 are arranged on a half circumference of the tubular portion 41 in the circumferential direction. However, the multiple advance supply ports SP1 may be arranged on the all circumference of the tubular portion 41 or the tubular portion 41 may have a single advance supply port SP2. The retard supply ports SP1 and the advance supply ports SP2 are in communication with the shaft hole portion 322 of the camshaft 320 shown in FIG. 1. As shown in FIGS. 3 and 4, the recycling ports 47 are defined between the retard protruding walls 43 and the advance protruding walls 44 in the axial direction AD and pass through the tubular portion 41 between the outer circumferential surface and the inner circumferential surface of the tubular portion 41. The recycling ports 47 are in communication with the retard supply ports SP1 and the advance supply ports SP2. Specifically, the recycling ports 47 are in communication with the retard supply ports SP1 through spaces that are defined between the inner circumferential surface of the main body 31 of the outer sleeve 30 and the outer circumferential surface of the tubular portion 41 of the inner sleeve 40 and that are defined between adjacent ones of the retard protruding walls 43 in the circumferential direction. The recycling ports 47 are in communication with the advance supply ports SP2 through spaces that are defined between the inner circumferential surface of the main body 31 of the outer sleeve 30 and the outer circumferential surface of the tubular portion 41 of the inner sleeve 40 and that are defined between adjacent ones of the advance protruding walls 44 in the circumferential direction. Therefore, the recycling ports 47 serve as a recycling mechanism for returning the hydraulic oil flowing out of the retard chambers 141 or the advance chambers 142 to a supply source. In the present embodiment, the multiple recycling ports 47 are formed adjacent to each other in the circumferential direction, but the tubular portion 41 may have a single recycling port 47. An operation of the valve timing adjustment device 100 including a switching of the oil channels by sliding the spool 50 will be described later.

As shown in FIG. 3, the bottom portion 42 is integrally formed with the tubular portion 41 and closes an end portion in the axial direction AD of the tubular portion 41 away from the solenoid 160 (in other words, an end portion of the tubular portion 41 closer to the camshaft 320). One end of the spring 60 is in contact with the bottom portion 42.

As shown in FIG. 4, the multiple retard protruding walls 43 protrude radially outward from the tubular portion 41 and are arranged adjacent to each other in the circumferential direction. The retard protruding walls 43 define the spaces therebetween in the circumferential direction. The spaces are in communication with the axial hole portion 322 of the camshaft 320 shown in FIG. 1 and the hydraulic oil supplied from the hydraulic oil supply source 350 flows through the spaces. As shown in FIGS. 3 and 4, the retard protruding walls 43 respectively define inner retard ports 23. Each of the inner retard ports 23 passes through the retard protruding wall 43 between an outer circumferential surface and an inner circumferential surface of the retard protruding wall 43. As shown in FIG. 3, the inner retard ports 23 are respectively in communication with the outer retard ports 21 defined in the outer sleeve 30. Each of the inner retard port 23 has an axis that is offset from an axis of the outer retard port 21 in the axial direction AD.

As shown in FIG. 4, the multiple advance protruding walls 44 are disposed between the retard protruding walls 43 and the solenoid 160 in the axial direction AD. The multiple advance protruding walls 44 protrude radially outward from the tubular portion 41 and are arranged adjacent to each other in the circumferential direction. The advance protruding walls 44 define the spaces therebetween in the circumferential direction. The spaces are in communication with the shaft hole portion 322 shown in FIG. 1 and the hydraulic oil supplied from the hydraulic oil supply source 350 flows through the spaces. As shown in FIGS. 3 and 4, the advance protruding walls 44 respectively define inner advance ports 24. Each of the inner advance port 24 passes through the advance protruding wall 44 between an outer circumferential surface and an inner circumferential surface of the advance protruding wall 44. As shown in FIG. 3, the inner advance ports 24 are respectively in communication with the outer advance ports 22 defined in the outer sleeve 30. Each of the inner advance ports 24 has an axis that is offset from an axis of the outer advance port 22 in the axial direction AD.

The sealing wall 45 protrudes radially outward from an entire circumference of the tubular portion 41. The sealing wall 45 is disposed between the advance supply ports SP2 and the solenoid 160 in the axial direction AD. The sealing wall 45 seals a clearance between the inner circumferential surface of the main body 31 of the outer sleeve 30 and the outer circumferential surface of the tubular portion 41 of the inner sleeve 40, thereby restricting the hydraulic oil flowing through a hydraulic oil supply passage 25, which will be described later, from leaking toward the solenoid 160. The sealing wall 45 has an outer diameter that is substantially the same as that of the retard protruding walls 43 and that of the advance protruding walls 44.

The flange portion 46 protrudes radially outward from an entire circumference of the tubular portion 41 at an end portion of the inner sleeve 40 closer to the solenoid 160. The flange portion 46 is arranged in the large diameter portion 36 of the outer sleeve 30. As shown in FIG. 4, the flange portion 46 includes multiple fitting portions 48. The multiple fitting portions 48 are arranged adjacent to each other in the circumferential direction at an outer edge of the flange portion 46. In the present embodiment, the fitting portions 48 are formed by cutting off an outer edge of the flange portion 46 straight. However, cutting shape is not limited to a straight shape and may be a curved shape. Fitting protrusions 73 of the fixing member 70, which will be described later, are fit to the fitting portions 48.

As shown in FIG. 3, the stopper 49 is formed at the end portion of the inner sleeve 40 closer to the camshaft 320 in the axial direction AD. The stopper 49 has an inner diameter smaller than those of other portions of the tubular portion 41 such that the end portion of the spool 50 closer to the camshaft 320 can come into contact with the stopper 49. The stopper 49 defines a sliding limit position of the spool 50 in a direction away from the electromagnetic portion 162 of the solenoid 160.

The axial hole 34 defined in the outer sleeve 30 and the inner sleeve 40 define a space therebetween and the space serves as the hydraulic oil supply passage 25. The hydraulic oil supply passage 25 is in communication with the shaft hole portion 322 of the camshaft 320 shown in FIG. 1 and guides the hydraulic oil supplied from the hydraulic oil supply source 350 to the retard supply ports SP1 and the advance supply ports SP2. As shown in FIG. 3, the outer retard ports 21 and the inner retard ports 23 form retard ports 27 that are in communication with the retard chambers 141 through the retard channels 137 shown in FIG. 2. As shown in FIG. 3, the outer advance ports 22 and the inner advance ports 24 form advance ports 28 that are in communication with the advance chambers 142 through the advance channels 138 shown in FIG. 2.

As shown in FIG. 3, at least a part, in the axial direction AD, of a clearance between the outer sleeve 30 and the inner sleeve 40 is sealed to restrict a leakage of the hydraulic oil. More specifically, the retard protruding walls 43 seal a clearance between the retard ports 27 and the retard supply ports SP1 and a clearance between the retard ports 27 and the recycling ports 47. The advance protruding walls 44 seal a clearance between the advance ports 28 and the advance supply ports SP2 and a clearance between the advance ports 28 and the recycling ports 47. Further, the sealing wall 45 seals a clearance between the hydraulic oil supply passage 25 and an outside of the hydraulic oil control valve 10. That is, an area in the axial direction AD between the retard protruding walls 43 and the sealing wall 45 is set as a sealing area SA. In the seal area SA, a radial clearance between the outer sleeve 30 and the inner sleeve 40 is minimized. Further, in the present embodiment, the main body 31 of the outer sleeve 30 has an inner diameter that is substantially constant in the sealing area SA.

The spool 50 is arranged radially inside of the inner sleeve 40. The spool 50 has ab end portion in contact with the solenoid 160 and is driven and moved by the solenoid 160 in the axial direction AD. The spool 50 has a spool tubular portion 51, a spool bottom portion 52, and a spring receiving portion 56. Further, the spool 50 defines a drain inlet 54, a drain outlet 55, and at least a portion of a drain passage 53.

The spool tubular portion 51 has a substantially tubular shape. The spool tubular portion 51 has, on an outer circumferential surface of the spool tubular portion 51, a retard sealing portion 57, an advance sealing portion 58, and a stopper 59. The retard sealing portion 57, the advance sealing portion 58, and the stopper 59 are arranged in this order from the end portion of the spool 50 closer to the camshaft 320 in the axial direction AD. Each of the retard sealing portion 57, the advance sealing portion 58, and the stopper 59 protrudes radially outward from an entire circumference of the spool tubular portion 51. The retard sealing portion 57 and the advance sealing portion 58 seal a part among the ports SP1, SP2, 27, 28, and 47 according to the sliding position of the spool 50. More specifically, as shown in FIG. 3, the retard sealing portion 57 blocks a communication between the recycling ports 47 and the retard ports 27 when the spool 50 is located at the closest position to the electromagnetic portion 162 of the solenoid 160. As shown in FIG. 5, the retard sealing portion 57 blocks a communication between the retard supply ports SP1 and the retard ports 27 when the spool 50 is located at the farthest position from the electromagnetic portion 162. As shown in FIG. 3, the advance sealing portion 58 blocks a communication between the advance supply ports SP2 and the advance ports 28 when the spool 50 is located at the closest position to the electromagnetic portion 162. As shown in FIG. 5, the advance sealing portion 58 blocks a communication between the recycling ports 47 and the advance ports 28 when the spool 50 is located at the farthest position from the electromagnetic portion 162. “Blocking a communication” is equivalent to sealing. The clearance between the inner sleeve 40 and the spool 50 in the radial direction is minimized in a portion where such sealing property is required. Since different portions in the axial direction AD are sealed according to a stroke of the spool 50, a sealing length in the axial direction AD of the portion that requires such sealing property is shorter than the stroke of the spool 50. Here, the “stroke of the spool 50” means a moving length of the spool 50 between a position where the spool 50 is closest to the electromagnetic portion 162 of the solenoid 160 and a position where the spool 50 is farthest from the electromagnetic portion 162. As shown in FIG. 3, the stopper 59 defines the sliding limit of the spool 50 in a direction toward the electromagnetic portion 162 of the solenoid 160 by coming into contact with the fixing member 70.

The spool bottom portion 52 is integrally formed with the spool tubular portion 51 and closes an end portion of the spool tubular portion 51 closer to the solenoid 160. The spool bottom portion 52 can protrude from the sleeve 20 toward the solenoid 160 in the axial direction AD. The spool bottom portion 52 serves as a proximal end portion of the spool 50.

A space surrounded by the spool tubular portion 51, the spool bottom portion 52, the tubular portion 41 of the inner sleeve 40, and the bottom portion 42 of the inner sleeve 40 functions as the drain passage 53. Therefore, the inner space of the spool 50 serves as at least a part of the drain passage 53. The hydraulic oil discharged from the retard chambers 141 and the advance chambers 142 flows through the drain passage 53.

The drain inlet 54 is defined in the spool tubular portion 51 between the retard sealing portion 57 and the advance sealing portion 58 in the axial direction AD. The drain inlet 54 passes through the spool tubular portion 51 between the outer circumferential surface and the inner circumferential surface of the spool tubular portion 51. The drain inlet 54 guides the hydraulic oil discharged from the retard chambers 141 and the advance chambers 142 into the drain passage 53. Further, the drain inlet 54 is in communication with the supply ports SP1 and SP2 through the recycling ports 47.

The spool bottom portion 52, which is an end of the spool 50, defines the drain outlet 55 opening radially outward. The hydraulic oil in the drain passage 53 flows out of the hydraulic oil control valve 10 through the drain outlet 55. As shown in FIG. 1, the hydraulic oil flowing out through the drain outlet 55 is collected in the oil pan 352.

As shown in FIG. 3, the spring receiving portion 56 is formed at an end portion of the spool tubular portion 51 closer to the camshaft 320 and has an inner diameter that is larger than those of other portions of the spool tubular portion 51. The other end of the spring 60 is in contact with the spring receiving portion 56.

In the present embodiment, each of the outer sleeve 30 and the spool 50 is made of iron and the inner sleeve 40 is made of aluminum. Therefore, the inner sleeve 40 has a coefficient of linear expansion larger than that of the outer sleeve 30 and that of the spool 50. Further, the outer sleeve 30 and the spool 50 are harder than the inner sleeve 40. Such hardness may be defined by a hardness measured by using an arbitrary hardness measuring method such as Rockwell hardness and Vickers hardness.

The spring 60 is composed of a compression coil spring and has one end in contact with the bottom portion 42 of the inner sleeve 40 and the other end in contact with the spring receiving portion 56 of the spool 50. The spring 60 biases the spool 50 toward the solenoid 160 along the axial direction AD.

The fixing member 70 is fixed to the end portion of the outer sleeve 30 closer to the solenoid 160. As shown in FIG. 4, the fixing member 70 includes a flat plate portion 71 and the multiple fitting protrusions 73.

The flat plate portion 71 has a flat plate shape extending in the radial direction. Extending direction of the flat plate portion 71 is not limited to the radial direction and may be another direction intersecting the axial direction AD. The flat plate portion 71 defines an opening 72 at a center of the flat plate portion 71. As shown in FIG. 3, the spool bottom portion 52, which is one end portion of the spool 50, is inserted into the opening 72.

As shown in FIG. 4, the multiple fitting protrusions 73 protrude from the flat plate portion 71 in the axial direction AD, and are arranged side by side in the circumferential direction. Protruding direction of the fitting protrusions 73 is not limited to the axial direction AD and may be any direction intersecting the radial direction. The fitting protrusions 73 fit to the fitting portions 48 of the inner sleeve 40 respectively.

As shown in FIG. 3, the spool 50 is inserted into the inner sleeve 40 and the fixing member 70 is assembled such that the fitting protrusions 73 fit to the fitting portions 48. After that, the fixing member 70 is deformed to be fixed to the outer sleeve 30. An outer edge of the end surface of the fixing member 70 facing the solenoid 160 serves as deformed portions 74 that are deformed to be fixed to the outer sleeve 30.

The fixing member 70 is fixed to the outer sleeve 30 while the fitting protrusions 73 fit to the fitting portions 48. Thus, the inner sleeve 40 is restricted from rotating in the circumferential direction relative to the outer sleeve 30. Further, the fixing member 70 is fixed to the outer sleeve 30, so that the inner sleeve 40 and the spool 50 are restricted from coming off from the outer sleeve 30 in the axial direction AD toward the solenoid 160.

The check valve 90 suppresses a backflow of the hydraulic oil. The check valve 90 includes two supply check valves 91 and a recycling check valve 92. As shown in FIG. 4, each of the supply check valves 91, and the recycling check valve 92 are formed by winding a band-shaped thin plate into an annular shape, so that each of the supply check valves 91 and the recycling check valve 92 can be elastically deformed in the radial direction. As shown in FIG. 3, each of the supply check valves 91 is arranged in contact with the inner circumferential surface of the tubular portion 41 at a position corresponding to the retard supply port SP1 or the advance supply port SP2. When each of the supply check valves 91 receives pressure of the hydraulic oil in the radial direction from an outside of the each of the supply check valves 91, an overlapping area of the band-shaped thin plate increases and the each of the supply check valves 91 shrinks in the radial direction. The recycling check valve 92 is arranged in contact with the outer circumferential surface of the tubular portion 41 at a position corresponding to the recycling port 47. When the recycling check valve 92 receives the pressure of the hydraulic oil in the radial direction from an inside of the recycling check valve 92, an overlapping area of the band-shaped thin plate decreases and expands in the radial direction.

In the hydraulic oil control valve 10 of the present embodiment, the fixing portion 32 is screwed into the shaft fixing portion 323, so that the axial force toward the camshaft 320 in the axial direction AD is applied and the hydraulic oil control valve 10 is fixed to the end portion 321 of the camshaft 320. The outer sleeve 30 is elastically deformed by the applied axial force and contracts in the radial direction. Thus, it is necessary to secure a radial clearance to restrict a deterioration of the slidability of the spool 50.

In the present embodiment, when the axial force is not applied to the outer sleeve 30, that is, before the hydraulic oil control valve 10 is fixed to the camshaft 320, a minimum clearance CL1 that is a minimum value of a radial clearance between the outer sleeve 30 and the inner sleeve 40 is designed to be larger than a minimum clearance CL2 that is a minimum value of a radial clearance between the inner sleeve 40 and the spool 50. More specifically, the minimum clearance CL1 between the inner circumferential surface of the main body 31 of the outer sleeve 30 and the outer circumferential surfaces of the retard protruding walls 43, the advance protruding walls 44, and the sealing walls 45 of the inner sleeve 40 in the radial direction is set to a value larger than the minimum clearance CL2 between the inner circumferential surface of the tubular portion 41 of the inner sleeve 40 and the outer circumferential surfaces of the retard sealing portion 57, the advance sealing portion 58, and the stopper 59 of the spool 50 in the radial direction. The reason for such a setting will be described below.

In the hydraulic oil control valve 10 of the present embodiment, different portions in the axial direction AD are sealed according to the stroke of the spool 50. Therefore, a length in the axial direction AD of the minimum clearance CL2 between the inner sleeve 40 and the spool 50 in the radial direction is shorter than the stroke of the spool 50. Thus, the hydraulic oil is more likely to leak through the minimum clearance CL2. Further, the inner sleeve 40 does not move relative to the outer sleeve 30 in the axial direction AD. Therefore, a length, in the axial direction AD, of the minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40 in the radial direction is set to a relatively long value. Therefore, the hydraulic oil is less likely to leak through the minimum clearance CL1. Thus, in case that radial clearances are secured to restrict the slidability of the spool 50 from deteriorating, an increase in an amount of leakage of the hydraulic oil can be suppressed by setting the minimum clearance CL1 through which the leakage of the hydraulic oil is less likely to occur to a value larger than the minimum clearance CL2 through which the leakage of the hydraulic oil is likely to occur, compared to a configuration in which a magnitude relationship of the radial clearances is different from that of the present embodiment.

In the present embodiment, the magnitude relationship between the minimum clearance CL1 and the minimum clearance CL2 is maintained even in a state where the axial force is applied to the outer sleeve 30 and the outer sleeve 30 is fixed to the end portion 321 of the camshaft 320.

In the present embodiment, the crankshaft 310 is a subordinate concept of the drive shaft in the present disclosure, the camshaft 320 is a subordinate concept of the driven shaft in the present disclosure, and the intake valve 330 is a subordinate concept of the valve in the present disclosure. Further, the solenoid 160 is a subordinate concept of the actuator in the present disclosure.

A-2. Operation of Valve Timing Adjustment Device

As shown in FIG. 1, the hydraulic oil supplied from the hydraulic oil supply source 350 to the supply inlet 326 flows into the hydraulic oil supply passage 25 through the shaft hole portion 322. When the solenoid 160 is not energized and the spool 50 is located at the closest position to the electromagnetic portion 162 of the solenoid 160 as shown in FIG. 3, the retard ports 27 are in communication with the retard supply ports SP1. As a result, the hydraulic oil in the hydraulic oil supply passage 25 is supplied into the retard chambers 141, the vane rotor 130 rotates in the retard direction relative to the housing 120, and a relative rotation phase of the camshaft 320 with respect to the crankshaft 310 is shifted in the retard direction. Further, in this state, the advance ports 28 are not in communication with the advance supply ports SP2 but in communication with the recycling ports 47. As a result, the hydraulic oil discharged from the advance chambers 142 is returned to the retard supply ports SP1 through the recycling ports 47 and recirculated. Further, a part of the hydraulic oil discharged from of the advance chambers 142 flows into the drain passage 53 through the drain inlet 54 and is returned to the oil pan 352 through the drain outlet 55.

When the solenoid 160 is energized and the spool 50 is located at the farthest position from the electromagnetic portion 162 of the solenoid 160 as shown in FIG. 5, i.e., when the spool is in contact with the stopper 49, the advance ports 28 are in communication with the advance supply ports SP2. As a result, the hydraulic oil in the hydraulic oil supply passage 25 is supplied into the advance chambers 142, the vane rotor 130 rotates in the advance direction relative to the housing 120, and the relative rotation phase of the camshaft 320 with respect to the crankshaft 310 is shifted in the advance direction. Further, in this state, the retard ports 27 are not in communication with the retard supply ports SP1 but in communication with the recycling ports 47. As a result, the hydraulic oil discharged from the retard chambers 141 is returned to the advance supply ports SP2 through the recycling ports 47 and recirculated. Further, a part of the hydraulic oil discharged from the retard chambers 141 flows into the drain passage 53 through the drain inlet 54 and is returned to the oil pan 352 through the drain outlet 55.

Further, as shown in FIG. 6, when the solenoid 160 is energized and the spool 50 is located substantially in the center of the sliding area, the retard ports 27 are in communication with the retard supply ports SP1 and the advance ports 28 are in communication with the advance supply ports SP2. As a result, the hydraulic oil in the hydraulic oil supply passage 25 is supplied into both the retard chambers 141 and the advance chambers 142, the vane rotor 130 is restricted from rotating relative to the housing 120, and the relative rotation phase of the camshaft 320 with respect to the crankshaft 310 is maintained.

The hydraulic oil supplied into the retard chamber 141 or the advance chamber 142 flows into the housing hole 132 through the retard chamber pin control oil channel 133 or the advance chamber pin control oil channel 134. Therefore, when sufficient hydraulic pressure is applied to the retard chambers 141 or the advance chambers 142 and the lock pin 150 comes off from the fitting recessed portion 128 against the biasing force of the spring 151 with the hydraulic oil flowing into the housing hole 132, the vane rotor 130 is allowed to rotate relative to the housing 120.

When the relative rotation phase of the camshaft 320 is advanced from the target phase, an energizing amount to the solenoid 160 is set to a relatively small value and the vane rotor 130 is rotated in the retard direction relative to the housing 120, As a result, the relative rotation phase of the camshaft 320 with respect to the crankshaft 310 is shifted in the retard direction and the valve timing is retarded. Further, when the relative rotation phase of the camshaft 320 is retarded from the target value, the energization amount to the solenoid 160 is set to a relatively large value and the vane rotor 130 is rotated in the advance direction relative to the housing 120. As a result, the relative rotation phase of the camshaft 320 with respect to the crankshaft 310 is shifted in the advance direction and the valve timing is advanced. Further, when the relative rotation phase of the camshaft 320 matches the target phase, the energization amount to the solenoid 160 is set to a medium value and the vane rotor 130 is restricted from rotating relative to the housing 120. As a result, the relative rotation phase of the camshaft 320 with respect to the crankshaft 310 is maintained and the valve timing is maintained.

According to the hydraulic oil control valve 10 of the valve timing adjustment device 100 of the first embodiment described above, the radial minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40 is larger than the radial minimum clearance CL2 between the inner sleeve 40 and the spool 50 when the axial force is not applied to the outer sleeve 30. Here, in the hydraulic oil control valve 10 of the present embodiment, different portions in the axial direction AD are sealed according to the stroke of the spool 50. Thus, a length, in the axial direction AD, of the minimum clearance CL2 between the inner sleeve 40 and the spool 50 in the radial direction is shorter than the stroke of the spool 50. Therefore, hydraulic oil leaks easily through the radial minimum clearance CL2 between the inner sleeve 40 and the spool 50. Further, the inner sleeve 40 does not move relative to the outer sleeve 30 in the axial direction AD. Therefore, a length, in the axial direction AD, of the minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40 in the radial direction is set to a relatively long value. Thus, the hydraulic oil is less likely to leak through the radial minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40. Thus, in case that radial clearances are secured to suppress a deterioration of the slidability of the spool 50 even if the axial force to fix the hydraulic oil control valve 10 deforms and contracts the outer sleeve 30 in the radial direction, an increase in an amount of the leakage of the hydraulic oil can be suppressed by setting the minimum clearance CL1 in which the leakage of the hydraulic oil is less likely to occur to a value larger than the minimum clearance CL2 in which the leakage of the hydraulic oil is likely to occur, compared to a configuration in which a magnitude relationship of the radial clearances is different from that of the present embodiment. Therefore, it is possible to suppress an increase in an amount of the leakage of the hydraulic oil while suppressing deterioration of the slidability of the spool 50.

Further, since the increase in an amount of the leakage of the hydraulic oil is suppressed by appropriately allocating the total value of the sizes of the minimum clearance CD and the minimum clearance CL2 to the minimum clearance CL1 and the minimum clearance CL2, it is possible to suppress an increase of the numbers of parts and an increase of assembly steps compared to a configuration in which a sealing member is arranged in the radial minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40 to restrict the leakage of the hydraulic oil. Therefore, it is possible to suppress an increase in the cost required for manufacturing the hydraulic oil control valve 10. Further, since the sealing material or the like can be omitted, it is possible to prevent the slidability of the spool 50 from deteriorating due to the sealing material sticking out toward the spool 50.

Further, since the inner sleeve 40 has a coefficient of linear expansion larger than that of the outer sleeve 30, the radial minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40 can be reduced as the temperature of the hydraulic oil control valve 10 is increased during the operation of the valve timing adjustment device 100. Thus, it is possible to further suppress an increase in the amount of the hydraulic oil leaking through the minimum clearance CL1.

Further, since the outer sleeve 30 is harder than the inner sleeve 40, the workability of the inner sleeve 40 can be improved while ensuring a strength of the fixing between the outer sleeve 30 and the end portion 321 of the camshaft 320. Thus, the workability of the ports SP1, SP2, 27, 28, 47 of the sleeve 20 can be improved, so that the manufacturing process for forming the ports SP1, SP2, 27, 28, 47 can be restricted from being complicated and an increase in the manufacturing cost can be suppressed.

Further, since the outer sleeve 30 is made of iron and the inner sleeve 40 is made of aluminum, both of a configuration in which the coefficient of linear expansion of the inner sleeve 40 is larger than that of the outer sleeve 30 and a configuration in which the outer sleeve 30 is harder than the inner sleeve 40 can be easily realized at the same time.

Further, since the sleeve 20 has a double-structure including the outer sleeve 30 and the inner sleeve 40, the hydraulic oil supply passage 25 can be easily realized by a clearance between the outer sleeve 30 and the inner sleeve 40 in the radial direction. Therefore, it is possible to restrict the hydraulic pressure from being applied to the spool 50 when supplying the hydraulic oil and to suppress deterioration of the slidability of the spool 50. Further, since the sleeve 20 has a double-structure, the workability of each of the ports SP1, SF2, 27, 28, and 47 can be improved and the manufacturing process of the sleeve 20 can be restricted from becoming complicated, Further, since the workability can be improved, the degree of freedom in designing each port SP1, SP2, 27, 28, 47 can be improved, and the mountability of the hydraulic oil control valve 10 and the valve timing adjustment device 100 can be improved.

B. Second Embodiment

A hydraulic oil control valve 10 of a second embodiment is different from the hydraulic oil control valve 10 of the first embodiment in the dimensional relationship between the minimum clearance CL1 and the minimum clearance CL2. Since the other configurations are the same as those in the first embodiment, the same configurations are designated by the same reference numerals, and detailed description thereof will be omitted.

When the hydraulic oil control valve 10 of the second embodiment is fastened to the end portion 321 of the camshaft 320, the outer sleeve 30 elastically deforms due to the applied axial force and contracts in the radial direction, so that the outer sleeve 30 comes into contact with the inner sleeve 40 in the radial direction. In other words, the radial minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40 becomes zero by fastening the outer sleeve 30. Thus, it is possible to suppress an increase in the amount of the hydraulic oil leaking through the radial minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40.

Further, also in the hydraulic oil control valve 10 of the second embodiment, the outer sleeve 30 and the spool 50 are each formed of iron and the inner sleeve 40 is formed of aluminum, as in the hydraulic oil control valve 10 of the first embodiment. Thus, the coefficient of linear expansion of the inner sleeve 40 is larger than the coefficient of linear expansion of the outer sleeve 30 and the inner sleeve 40 thermally expands more than the outer sleeve 30. However, when the temperature of the hydraulic oil control valve 10 is increased due to the operation of the valve timing adjustment device 100, the outer sleeve 30 and the inner sleeve 40 are already in contact with each other in the radial direction, so that the inner sleeve 40 is restricted from expanding in the radial direction. Therefore, it is possible to suppress an increase in the radial minimum clearance CL2 between the inner sleeve 40 and the spool 50 as the temperature of the hydraulic oil control valve 10 is increased, so that it is possible to suppress an increase in the amount of the hydraulic oil leaking through the minimum clearance CL2. Further, since the coefficient of linear expansion of the spool 50 is similar to or the same as the coefficient of linear expansion of the outer sleeve 30, it is possible to suppress a change in the size of the minimum clearance CL2 due to an increase in the temperature of the hydraulic oil control valve 10. Therefore, deterioration of the slidability of the spool 50 can be suppressed. The description “the coefficient of linear expansion of the spool 50 is similar to or the same as the coefficient of linear expansion of the outer sleeve 30” is not limited to the case where the coefficient of linear expansion of the spool 50 is equal to the coefficient of linear expansion of the outer sleeve 30. For example, the coefficient of linear expansion of the spool 50 may be within the range of plus or minus about 20% of the coefficient of linear expansion of the outer sleeve 30. Further, since the coefficient of linear expansion of the spool 50 is less than the coefficient of linear expansion of the inner sleeve 40, it is possible to restrict the minimum clearance CL2 from being excessively reduced as the temperature of the hydraulic oil control valve 10 is increased, thereby suppressing the deterioration of the slidability of the spool 50.

In the present embodiment, the state in which the outer sleeve 30 is fastened to the end portion 321 of the camshaft 320 is a subordinate concept of a state where a predetermined condition including a condition in which the axial force is applied is satisfied in the present disclosure.

According to the hydraulic oil control valve 10 of the second embodiment described above, the outer sleeve 30 and the inner sleeve 40 are in contact with each other in the radial direction when the axial force is applied, thereby suppressing an increase in the amount of the hydraulic oil leaking through the radial minimum clearance CL1 between the outer sleeve 30 and the inner sleeve 40. Further, since the contact between the outer sleeve 30 and the inner sleeve 40 in the radial direction can restrict the inner sleeve 40 from expanding in the radial direction, an increase in the radial minimum clearance CL2 between the inner sleeve 40 and the spool 50 can be suppressed and an increase in the amount of the hydraulic oil leaking through the minimum clearance CL2 can be suppressed. Thus, even in a configuration where the radial minimum clearance CL2 between the inner sleeve 40 and the spool 50 is secured to suppress the deterioration of the slidability of the spool 50, an increase in an amount of the leakage of the hydraulic oil can be suppressed. That is, an increase in the amount of the leakage of the hydraulic oil is suppressed while suppressing the deterioration of the slidability of the spool 50.

Further, since the coefficient of linear expansion of the spool 50 is similar to or the same as the coefficient of linear expansion of the outer sleeve 30, it is possible to suppress a change in the size of the minimum clearance CL2 caused by an increase in the temperature of the hydraulic oil control valve 10 and to suppress the deterioration of the slidability of the spool 50. Further, since the outer sleeve 30 and the spool 50 are made of iron and the inner sleeve 40 is made of aluminum, both of a configuration in which the inner sleeve 40 has the coefficient of linear expansion larger than that of the outer sleeve 30 and a configuration in which the spool 50 has the coefficient of linear expansion similar to or same as that of the outer sleeve 30 can be easily realized at the same time. Further, since the spool 50 is made of iron, it is possible to suppress a decrease in the strength of the spool 50. Thus, it is unnecessary to dispose a member different from the spool 50 in a contact portion between the spool bottom portion 52 of the spool 50 and the shaft 164 of the solenoid 160 to suppress wear caused by the rotation of the hydraulic oil control valve 10. As a result, it is possible to suppress an increase in the number of parts of the hydraulic oil control valve 10 and to prevent the assembly process from becoming complicated. Thus, it is possible to suppress an increase in the cost required for manufacturing the hydraulic oil control valve 10.

C. Third Embodiment

A hydraulic oil control valve 10 of a third embodiment is different from the hydraulic oil control valve 10 of the second embodiment in the dimensional relationship between the minimum clearance CL1 and the minimum clearance CL2. Since the other configurations are the same as those in the second embodiment, the same configurations are designated by the same reference numerals, and detailed description thereof will be omitted.

In the hydraulic oil control valve 10 of the third embodiment, the outer sleeve 30 and the inner sleeve 40 come into contact with each other in the radial direction as the temperature increases during the operation of the valve timing adjustment device 100. In other words, the radial minimum clearance CU between the outer sleeve 30 and the inner sleeve 40 becomes zero as the temperature of the internal combustion engine 300 increases. Thus, it is possible to suppress an increase in the amount of the hydraulic oil leaking through the radial minimum clearance CU between the outer sleeve 30 and the inner sleeve 40. A difference between the temperature of the valve timing adjustment device 100 during the operation of the valve timing adjustment device 100 and that before the operation may be less than or equal to 100° C., or about 150° C., or 200° C. or higher.

Further, also in the hydraulic oil control valve 10 of the third embodiment, the outer sleeve 30 and the spool 50 are each formed of iron and the inner sleeve 40 is formed of aluminum, as in the hydraulic oil control valve 10 of the second embodiment. Thus, the coefficient of linear expansion of the inner sleeve 40 is larger than the coefficient of linear expansion of the outer sleeve 30, and the inner sleeve 40 thermally expands more than the outer sleeve 30. However, when the temperature of the hydraulic oil control valve 10 is increased due to the operation of the valve timing adjustment device 100, the outer sleeve 30 and the inner sleeve 40 are in contact with each other in the radial direction, so that the inner sleeve 40 is restricted from expanding in the radial direction. Therefore, it is possible to suppress an increase in the radial minimum clearance CL2 between the inner sleeve 40 and the spool 50 as the temperature of the hydraulic oil control valve 10 is increased, and an increase in the amount of the hydraulic oil leaking through the minimum clearance CL2 can be suppressed. Further, since the coefficient of linear expansion of the spool 50 is similar to or the same as the coefficient of linear expansion of the outer sleeve 30, it is possible to suppress a change in the size of the minimum clearance CL2 caused by an increase in the temperature of the hydraulic oil control valve 10. Therefore, deterioration of the slidability of the spool 50 can be suppressed.

In the present embodiment, the state where the temperature is increased during the operation of the valve timing adjustment device 100 corresponds to a subordinate concept of a state where a predetermined condition including a condition where the axial force is applied and an ambient temperature of an environment where the valve timing adjustment device 100 is used is increased compared to that before the axial force is applied is satisfied in this disclosure. Further, the temperature of the internal combustion engine 300 corresponds to a subordinate concept of the ambient temperature of the environment where the valve timing adjustment device 300 is used.

According to the hydraulic oil control valve 10 of the third embodiment described above, effects similar to those of the hydraulic oil control valve 10 of the second embodiment can be obtained. In addition, when the axial force is applied to the hydraulic oil control valve 10 and the temperature is increased compared to that before the axial force is applied, the outer sleeve 30 and the inner sleeve 40 are in contact with each other in the radial direction, so that the outer sleeve 30 is restricted from receiving an excessive load in the radial direction.

D. Other Embodiments

(1) In each of the above-described embodiments, each of the outer sleeve 30 and the spool 50 is made of iron and the inner sleeve 40 is made of aluminum. However, the present disclosure is not limited to this. For example, the inner sleeve 40 may be formed of any other metal material, or may be formed of a resin material such as polyphenylene sulfide resin, nylon, or phenol resin. Further, the inner sleeve 40 may be made of the same material as the outer sleeve 30 and the spool 50. In an embodiment in which the inner sleeve 40 is made of resin, the outer sleeve 30 can be easily configured to be harder than the inner sleeve 40. Further, for example, the outer sleeve 30 and the spool 50 may be formed of any metal material such as stainless steel, or the outer sleeve 30 and the spool 50 may be formed of different materials. Further, for example, the coefficient of linear expansion of the inner sleeve 40 may not be larger than the coefficient of linear expansion of the outer sleeve 30, and the outer sleeve 30 may not be harder than the inner sleeve 40. Further, the coefficient of linear expansion of the spool 50 may not be similar to or equal to the coefficient of linear expansion of the outer sleeve 30. Such a configuration also achieves the same effects as those of the embodiment described above.

(2) In the above-described first embodiment, the magnitude relationship between the minimum clearance CU and the minimum clearance CL2 is maintained even in a state where an axial force is applied to the outer sleeve 30 and the outer sleeve 30 is fixed to the end portion 321 of the camshaft 320, but is not limited to. Even with such a configuration, the same effect as that of the first embodiment can be obtained.

(3) The configurations of the hydraulic oil control valves 10 in the above embodiments are examples and may be variously altered. For example, as in the hydraulic oil control valve 10 a of another third embodiment shown in FIG. 7, an end portion 401 of an inner sleeve 40 a closer to the camshaft 320 may define an opening 402 and an end portion 510 of a spool 50 a may be inserted into the opening 402. Further, the stopper 49 of the inner sleeve 40 a may be omitted, and a stopper 85 may be formed at a position of an outer sleeve 30 a facing the end portion 510 of the spool 50, In such a configuration, the end portion of the outer sleeve 30 a closer to the camshaft 320 may define a drain outlet 55 a and an inner space of an axial hole 34 a between the stopper 85 and the camshaft 320 may serve as a drain passage 53 a with the inner space of the spool 50. Further, in such a configuration, a main body 31 a of the outer sleeve 30 a may define a supply hole 328 through which the hydraulic oil is supplied from the hydraulic oil supply source 350. Further, a spool bottom portion 52 a of the spool 50 a may not protrude toward the solenoid 160 from the fixing member 70, the large diameter portion 36 of the outer sleeve 30 a may be omitted, and a stopper end portion 46 a that has a diameter substantially the same as that of the sealing wall 45 having an outer diameter substantially the same as that of the sealing wall 45 may be formed in place of the flange portion 46 of the inner sleeve 40 a. Such a configuration also achieves the same effects as those of the embodiment described above.

Further, for example, the recycling mechanism with the recycling ports 47 may be omitted. Further, for example, the inner space of the spool 50 may be configured as the hydraulic oil supply passage 25, and a space between the axial hole 34 of the outer sleeve 30 and the outer circumferential surface of the inner sleeve 40 may be configured as the drain passage 53. Further, a fixing method of the hydraulic oil control valve 10 to the end portion 321 is not limited to fastening between the male thread portion 33 and the female thread portion 324. The hydraulic oil control valve 10 may be fixed to the end portion 321 of the camshaft 320 with an axial force in the axial direction AD by any fixing method such as welding. Further, the present disclosure is not limited to the solenoid 160 and the hydraulic oil control valve 10 may be driven by any actuators such as an electric motor and an air cylinder. Such a configuration also achieves the same effects as those of the embodiment described above.

(4) In each of the above embodiments, the valve timing adjustment device 100 adjusts the valve timing of the intake valve 330 that is opened or closed by the camshaft 320, but the valve timing adjustment device 100 may adjust the valve timing of the exhaust valve 340. Further, the valve timing adjustment device 100 may be fixed to the end portion 321 of the camshaft 320 as a driven shaft to which a driving force is transmitted from the crankshaft 310 as the driving shaft through an intermediate shaft, or may be fixed to one of the end portion of the drive shaft and the end portion of the driven shaft which are included in the camshaft having the double structure.

The present disclosure should not be limited to the embodiments described above, and various other embodiments may be implemented without departing from the scope of the present disclosure. For example, the technical features in each embodiment corresponding to the technical features in the form described in the summary may be used to solve some or all of the above-described issues, or to provide one of the above-described effects. In order to achieve a part or all, replacement or combination can be appropriately performed. Also, if the technical features are not described as essential in the present specification, they may be omitted as appropriate. 

What is claimed is:
 1. A hydraulic oil control valve for a valve timing adjustment device, the valve timing adjustment device being configured to adjust valve timing of a valve and fixed to an end portion of one shaft that is a drive shaft or a driven shaft, the driven shaft being configured to selectively open and close the valve with a driving force transmitted from the drive shaft, the hydraulic oil control valve being coaxially disposed with a rotational axis of the valve timing adjustment device and configured to control a flow of a hydraulic oil supplied from a hydraulic oil supply source, the hydraulic oil control valve comprising: a tubular sleeve; and a spool that has an end portion in contact with an actuator and that is slidably moved by the actuator in an axial direction within the sleeve, wherein the sleeve includes: an inner sleeve disposed radially outside of the spool; and an outer sleeve defining an axial hole therein extending in the axial direction, the inner sleeve being inserted into at least a portion of the axial hole, the outer sleeve is configured to be fixable to the end portion of the one shaft by an axial force applied to the outer sleeve in the axial direction, and in absence of the axial force, a minimum clearance in a radial direction between the outer sleeve and the inner sleeve is larger than a minimum clearance in the radial direction between the inner sleeve and the spool,
 2. The hydraulic oil control valve according to claim 1, wherein the inner sleeve has a coefficient of linear expansion greater than that of the outer sleeve.
 3. The hydraulic oil control valve according to claim wherein the outer sleeve is harder than the inner sleeve.
 4. The hydraulic oil control valve according to claim 1, wherein the outer sleeve is made of iron, and the inner sleeve is made of aluminum or resin,
 5. A hydraulic oil control valve for a valve timing adjustment device, the valve timing adjustment device being configured to adjust valve timing of a valve and fixed to an end portion of one shaft that is a drive shaft or a driven shaft, the driven shaft being configured to selectively open or close the valve with a driving force transmitted from the drive shaft, the hydraulic oil control valve being coaxially disposed with a rotational axis of the valve timing adjustment device and configured to control a flow of a hydraulic oil supplied from a hydraulic oil supply source, the hydraulic oil control valve comprising: a tubular sleeve; and a spool that has an end portion in contact with an actuator and that is slidably moved by the actuator in an axial direction within the sleeve, wherein the sleeve includes: an inner sleeve disposed radially outside of the spool; and an outer sleeve defining an axial hole therein extending in the axial direction, the inner sleeve being inserted into at least a portion of the axial hole, the outer sleeve is configured to be fixable to the end portion of the one shaft of the drive shaft or the driven shaft by an axial force applied to the outer sleeve in the axial direction, when a predetermined condition is satisfied, the outer sleeve is in contact with the inner sleeve in a radial direction, and the predetermined condition includes a condition where the axial force is applied to the outer sleeve,
 6. The hydraulic oil control valve according to claim 5, wherein an ambient temperature is defined as an ambient temperature at which the valve timing adjustment device is used, and the predetermined condition further includes a condition where the ambient temperature after the axial force is applied to the outer sleeve is increased compared to the ambient temperature prior to applying the axial force to the outer sleeve.
 7. The hydraulic oil control valve according to claim 5, wherein the inner sleeve has a coefficient of linear expansion greater than that of the outer sleeve, and the spool has a coefficient of linear expansion same as or similar to that of the outer sleeve.
 8. The hydraulic oil control valve according to claim 7, wherein the outer sleeve and the spool are made of iron, and the inner sleeve is made of aluminum or resin.
 9. A valve timing adjustment device comprising a hydraulic oil control valve according to claim
 1. 